which engine?

[Buckman]

Guys, my engine went south the other day so now I'm having a new 355 built. My problem is do I won't a engine with a lot of hp or a engine with a lot of torque? Which one would get the best fuel mileage. The truck will be my daily driver and I would like to get good gas mileage out of it. I will not be pulling anything with it. It has 3.73 gears which I will be replacing with 3.08. The truck is a 71 gmc swb. Thx

[Old Yeller 1970]

Build it with a lot of torque and the HP will come with it. If you go for HP the torque on the bottom end suffers too much esp. with 3.07:1 rear gears.
Building for torque will get a lot better gas milage than if you just go all out for HP.

[Longhorn Man]

To add to what he said, build it so there is a lot of torque from 1500 to 2600 RPM or so.. you'll spend 75% of your driving time in that range and if it is cruising effortlessly, then your MPG will end up being better

[Old Yeller 1970]

One of the main factors (and one of the most fun and one of the biggest headaches) is choosing the right cam.

If economy and low end torque is your game you don't want the one I have in my sig. The 280 makes gobs of torque but not till 1200 RPM's and it barely idles at 900 RPM's. Since I have a 4-speed I can get away with it even though I have a 3.07:1 rear end.

For your truck I'd suggest one of the following as a starting point. The 260 starts making torque right from 600 RPM's and the 268 begins making torque at 800. Obviously the 260 will get better fuel milage than the 268 and will be a big improvement in power over a stock cam but the 268 will make significantly more power, even from idle, vs the 260.

260H High Energy™ is the perfect cam for vans, family sedans, pickups and tow vehicles.
This cam provides exceptional power and a gas mileage increase, especially on the highway. With its great torque and throttle response, the 260H cam can also be used for O.E.M. replacement in most big block applications. The 260H’s idle is smooth in large engines with stock exhaust systems. With headers, the 260H will produce a slight exhaust sound.

268H High Energy™ is our most versatile cam.
It is a great high performance cam for small blocks and a powerful cam for big blocks. With its noticeable idle and great all-around power, the 268H cam is great for daily driven performance vehicles. The 268H cam is an ideal cam for pickup drivers who want major power increases. It is also good for big blocks towing heavy loads equipped with lower optional rear end gears.

http://www.compcams.com/information/Products/Camshafts/

[68C15]

just remember HP is a mathemetical derivative of torque.

I am quite pleased with the Torque master from www.crower.com
or the one I REALLY like is grind # 00210. add in a set of 882 heads with gasket matching to a fel-pro 1205 & light pocket work, some .125 domes, a Weiand Stealth intake & HIGHLY modified Holley 4776. I squeazed 17 MPG on the highway with a 8600 pound truck & nothing short of amazing throttle response. not to mention how I could blow away a Bonneville SSI.